Patent application title: Coreless Roll of Web Material, Machine and Method for its Production

Abstract:

A method is described for obtaining a coreless roll (R) of web material
with a first portion of web material forming an inner nucleus (R1) of
said roll and a second portion of web material (R2) wound around the
outside of said nucleus. The two portions (R1, R2) can be separated from
one another and, for said purpose, an interface or discontinuity is
created in at least one turn of the web material forming the roll,
between said inner nucleus and said second portion of web material, so as
to facilitate the extraction of the inner nucleus from the outer portion
of the roll.

Claims:

1-73. (canceled)

74. A roll of coreless web material comprising a first portion of web
material forming an inner nucleus of said roll, and a second portion of
web material wound around outside said inner nucleus, wherein between
said first portion forming said inner nucleus and said second portion
wound around the outside of said inner nucleus is an interface that
facilitates mutual sliding between said first portion and said second
portion.

75. The roll as claimed in claim 74, wherein said interface comprises a
separator material applied to at least one turn of web material coming
between said inner nucleus and said second portion of the web material,
said separator material facilitating extraction of said inner nucleus
from said second portion of the roll.

76. The roll as claimed in claim 75, wherein said separator material is
applied over a length of web material corresponding to approximately half
a turn to approximately one turn of the web material.

77. The roll as claimed in claim 75, wherein said separator material is
applied in line with a transverse perforation line on the web material.

78. The roll as claimed in claim 75, wherein said separator material is
applied to at least one side of the web material.

79. The roll as claimed in claim 75, wherein said separator material is a
sheet material.

80. The roll as claimed in claim 79, wherein said separator material is
made of paper.

81. The roll as claimed in claim 79, wherein said separator material is
made of plastic.

82. The roll as claimed in claim 75, wherein said separator material
adheres to the web material forming the roll.

83. The roll as claimed in claim 82, wherein said separator material is
adhered to the web material forming the roll by an adhesive, crimping,
embossing, or electrostatic charges.

84. The roll as claimed in claim 79, wherein said separator material is
applied to both sides of the web material forming the roll.

85. The roll as claimed in claim 84, wherein said separator material
comprises two staggered sheets of web material inserted in said roll.

86. The roll as claimed in claim 85, wherein said two staggered sheets are
arranged so that when a center of said inner nucleus of the roll is
pressed to make said inner nucleus slide axially with respect to the
second portion, inducing tearing of the web material along a perforation
line present therein, a first sheet of said two staggered sheets remains
wound around the inner nucleus, and a second sheet of said two staggered
sheets remains inside a hole created in a remainder of the roll following
extraction of said inner nucleus.

87. The roll as claimed in claim 86, wherein said perforation line is
positioned in an intermediate area between two ends of the two staggered
sheets of separator material.

88. The roll as claimed in claim 75, wherein said separator material is a
sheet material with a leading end and a tail end, that is attached to the
web material in a vicinity of the leading end, while the tail end is
positioned in a vicinity of a perforation line in the web material.

89. The roll as claimed in claim 75, wherein said separator material is a
sheet material with a leading end and a tail end, that is attached to the
web material in a vicinity of the leading end, and said leading end is
positioned in a vicinity of a perforation line in the web material.

90. The roll as claimed in claim 88, wherein said sheet material is
anchored to the web material in a vicinity of both the leading end and
the tail end.

91. The roll as claimed in claim 74, wherein said interface comprises a
variation in winding density of said web material.

92. The roll as claimed in claim 91, wherein said interface is formed by a
portion of the web material wound more loosely than the winding density
of the first portion and of the second portion of said roll.

93. The roll as claimed in claim 92, wherein said interface is formed by a
portion of the web material wound more loosely, over a length of the web
material ranging between half a turn and fifty turns.

94. The roll as claimed in claim 74, wherein said interface comprises of
one or more turns formed by a length of web material and having a
different surface structure from the web material forming said first
portion and said second portion.

95. The roll as claimed in claim 94, wherein said length of web material
has a lower surface roughness than the web material forming said first
portion and said second portion.

96. The roll as claimed in claim 94, wherein said length of web material
is calendered.

97. The roll as claimed in claim 74, wherein said web material is made of
paper.

98. The roll as claimed in claim 74, wherein said inner nucleus has a
diameter of between 0.5 and 5 cm.

99. Method for manufacturing a coreless roll of web material, comprising
providing a first central portion of web material forming a nucleus,
winding a second portion of web material around said first central
portion, providing an interface between said first portion and said
second portion, wherein said interface is constructed and arranged to
facilitate extraction of said first portion from said second portion.

100. The method as claimed in claim 99, comprising steps as
follows:winding a first length of web material to form said first central
portion;creating said interface;winding a second length of web material
to form said second portion.

101. The method as claimed in claim 99, comprising steps as
follows:curling a free end of a first length of said web material and
winding the first length of the web material to form the first portion
creating the nucleus of said roll;creating the interface in said
winding;continuing to wind on a second length of web material to form the
second portion of web material wound around said first portion of web
material to complete said roll, said interface being arranged between
said first portion and said second portion.

102. The method as claimed in claim 99, further comprising said interface
is provided by applying a separator material to at least one side of said
web material in a length of the web material between said first portion
and said second portion.

103. The method as claimed in claim 102, wherein said separator material
is applied to both sides of said web material.

104. The method as claimed in claim 102, wherein said web material
includes transverse perforation lines spaced equidistant from each other,
and wherein said separator material is applied in line with at least one
of said perforation lines.

105. The method as claimed in claim 104, wherein said separator material
is applied downstream from one perforation line of said transverse
perforation lines.

106. The method as claimed in claim 105, wherein said separator material
includes a leading end and a tail end, and said separator material is
applied with the leading end positioned upstream from said one
perforation line and with the tail end positioned approximately in line
with said one perforation line.

107. The method as claimed in claim 102, wherein said separator material
is a bulk material applied to a surface of the web material.

108. The method as claimed in claim 107, wherein said bulk material is
applied by spraying or spreading.

110. The method as claimed in claim 102, wherein said separator material
is a sheet material.

111. The method as claimed in claim 110, wherein said sheet material is
made of plastic.

112. The method as claimed in claim 110, wherein said sheet material is
made of paper.

113. The method as claimed in claim 110, wherein said sheet material is
attached to a surface of the web material forming the roll.

114. The method as claimed in claim 113, wherein said sheet material is
glued to the surface of the web material.

115. The method as claimed in claim 99, wherein said interface is provided
by varying the web material winding density.

116. The method as claimed in claim 115, wherein said interface is
provided by a localized reduction in the winding density, said first
portion of web material and said second portion of web material being
wound with a greater winding density than the winding density of one or
more turns of web material coming between said first portion and said
second portion.

117. The method as claimed in claim 99, wherein said interface comprises
one or more turns of a stretch of web material having a surface structure
different from a surface structure of the web material forming said first
portion and said second portion.

118. The method as claimed in claim 117, wherein said stretch of web
material has a lower surface roughness than the surface structure of said
first portion and said second portion.

119. The method as claimed in claim 117, wherein said stretch of web
material is calendered.

120. The method as claimed in claim 102, wherein a first length of web
material that is wound before the separator material is applied, forms
the nucleus with a diameter of between 0.5 and 5 cm.

121. The method as claimed in claim 99, wherein said web material forming
the roll is paper.

122. The method as claimed in claim 99, wherein said interface is provided
by combining of at least two of a separator material, a localized
variation in winding density, and a change in at least one surface
feature of the web material.

123. A rewinder machine for manufacturing coreless rolls of web material,
comprising a winding unit wherein the web material is wound up around a
free end thereof to form a roll with a central nucleus forming a first
portion and an outer portion around the central nucleus forming a second
portion, including devices which can be enabled during winding of each
roll to create an interface between said first portion and said second
portion.

124. The machine as claimed in claim 123, wherein said devices comprise an
applicator of a separator material on the web material being wound, said
applicator being operated so as to apply said separator material after
said central nucleus has been formed.

125. The machine as claimed in claim 123, further comprising a peripheral
winding unit.

126. The machine as claimed in claim 125, wherein said peripheral winding
unit includes a first winder roller and a second winder roller defining a
nip for passage of the web material, said web material being fed around
said first winder roller.

127. The machine as claimed in 123, further comprising an oscillating
member which cooperates with the first winder roller and presents a
concave surface that forms a channel with said first winder roller in
which first turns of said nucleus are wound up.

128. The machine as claimed in claim 126, wherein said applicator is
situated upstream from the nip between the first winder roller and the
second winder roller in a forward feed direction of the web material.

129. The machine as claimed in claim 127, wherein said applicator is
situated upstream from said oscillating member in a forward feed
direction of the web material.

130. The machine as claimed in claim 124, wherein said applicator is
constructed and arranged to apply said separator material to both sides
of said web material.

131. The machine as claimed in claim 124, wherein said applicator
comprises an application means for applying a bulk separator material to
at least one side of said web material.

132. The machine as claimed in claim 131, wherein said applicator
comprises one or more application means selected from nozzles, rollers,
distributor blades, brushes, spreading means, sprayers, and combinations
thereof.

133. The machine as claimed in claim 124, wherein said applicator
comprises at least one separator material sheet feeder.

134. The machine as claimed in claim 133, wherein said applicator
comprises two separator material sheet feeders for applying sheets of
separator material on opposite sides of said web material.

135. The machine as claimed in claim 133, wherein said applicator
comprises at least one device for attaching a sheet of separator material
to said web material.

136. The machine as claimed in claim 135, wherein said at least one device
comprises a distributor of adhesive for gluing the sheet of separator
material to said web material.

137. The machine as claimed in claim 133, wherein said applicator
comprises at least one roller constructed and arranged to deliver sheets
of separator material.

138. The machine as claimed in claim 134, further comprising two
cooperating rollers, arranged on opposite sides of a path for the web
material, each of said two rollers being associated with one of said
sheet feeders, said two rollers applying staggered sheets of web material
to opposite sides of the web material.

139. The machine as claimed in claim 124, further comprising a perforator
that generates transverse perforation lines on the web material, and
wherein said applicator of separator material is synchronized with said
perforator so as to apply said separator material in a predetermined
position with respect to at least one transverse perforation line
generated by said perforator.

140. The machine as claimed in claim 124, further comprising a winding
cradle including a first winder roller, a second winder roller that,
together with the first winder roller, forms a nip through which the web
material being wound is passed, and a third winder roller which is
axially mobile, and wherein said applicator is associated with said third
winder roller.

141. The machine as claimed in claim 140, wherein said third winder roller
has a controlled suction effect arranged to apply sheets of the separator
material to the central nucleus of each log being formed in the winding
cradle.

142. The machine as claimed in claim 123, wherein said devices comprise a
system for temporarily varying winding density of the web material, which
can be temporarily enabled during winding of each roll to generate said
interface by a change in the winding density.

143. The machine as claimed in claim 142, wherein said system is arranged
to generate a localized variation in the winding density coinciding with
said interface.

144. The machine as claimed in claim 125, wherein said devices comprise an
element for locally modifying surface structure of the web material.

145. The machine as claimed in claim 144, wherein said element is
constructed and arranged to reduce surface roughness of the web material
in a stretch of the web material forming an interface between the first
portion and the second portion of each roll.

146. The machine as claimed in claim 144, wherein said element comprises a
calender.

Description:

TECHNICAL FIELD

[0001]The present invention relates to improvements to the production of
rolls of web material, such as paper, and so-called tissue paper in
particular. The invention specifically concerns improvements to the
machines and to the manufacturing methods, as well as to the rolls of
material.

STATE OF THE ART

[0002]Rolls of toilet paper, kitchen towels and other tissue paper
products are usually wound around winding cores or tubes made of
cardboard or other material. These winding cores are inserted in the
rewinder machine and the required quantity of paper is wound around them.
The resulting rolls, called logs, are subsequently cut into smaller
rolls, i.e. of lesser axial length, destined for the consumer. The
winding cores are normally made in machines in which two or more strips
of cardboard are helicoidally wound around a spindle. These machines, and
the material needed to manufacture the winding cores, represent a cost
with a considerable influence on that of the end product, as well as
adding to the complexity of the production line. To avoid the need to use
winding cores and to obtain products in rolls that contain a larger
quantity of wound material, various systems, methods and machines have
been studied that enable rolls to be manufactured without using a winding
core or central tube. Examples of such machines and methods are described
in U.S. Pat. Nos. 5,603,467; 5,538,199; 5,639,046; 5,690,296; 5,839,680.

[0003]The rolls obtained by means of these techniques have a compact
appearance and no empty areas in the middle. This can represent a
drawback for their use, in that the majority of the dispensers for
products in roll form have an axial holder that is inserted in the hole
of the winding cores on which such products are usually wound. The
absence of such a central hole has effectively restricted the use of
rolls obtained by the above-mentioned machines and methods, despite
products without winding cores offer considerable advantages, including a
greater quantity of wound paper for the same outer diameter of the roll,
the absence of core-making machinery in the production line, savings on
the raw materials (glues, cardboard) needed to manufacture the tubular
cores, an easier procedure for cutting the logs into rolls, and the lack
of waste material (the central core) after the rolls have been used up.

OBJECTS AND SUMMARY OF THE INVENTION

[0004]An object of the present invention is to provide a roll that offers
the advantages of rolls without a winding core, but without presenting
the above-mentioned characteristic drawbacks. Another object is to
provide a roll with innovative characteristics if compared with
traditional rolls.

[0005]According to another aspect, an object of the invention is to
provide a rewinder system or machine that enables a new type of roll to
be manufactured without any central winding core, without the
previously-discussed drawbacks and with innovative features if compared
with conventional products.

[0006]A further object of the present invention is to provide a winding
method for manufacturing a new type of roll without a central core and
with other innovative characteristics.

[0007]Basically, according to a first aspect, the invention relates to a
roll of web material with no central winding core, wherein a first
portion of web material forms the inner nucleus of the roll, and a second
portion of web material is wound around the outside of said nucleus, and
wherein a separator material is applied to at least one turn of the web
material coming between said inner nucleus and said second portion of web
material, covering a length corresponding to at least approximately half
a turn of web material.

[0008]The presence of this separator material between the nucleus portion
and the outer portion of the roll enables the nucleus to be extracted
from the remainder of the roll, tearing the web material in line with the
interface between the inner portion of the roll forming the nucleus and
the outer portion forming the remainder of the roll. In this way, the
roll originating as a solid, completely full configuration, thus avoiding
the need for a winding core or spindle, offers all the advantages
deriving from the absence both of a central winding core and of a central
hole during the manufacturing process and also during distribution,
whereas the end users can choose whether to use the roll whole, e.g. when
they have an adequate dispenser available, which has no axial roll
holder, or to slide the nucleus out of the roll, leaving the remainder of
the roll with a central hole of suitable dimensions (of the range of 1.5
to 3 cm, for instance) to enable its insertion on the axial holder of a
conventional dispenser. In addition to this dual usage option, the
central nucleus that is extracted from the outer portion of the roll is
also a product suitable for use by the consumer. For instance, the
central nucleus of a roll of tissue paper, such as a roll of toilet
paper, could also be used as a compact, portable toilet roll for carrying
in a handbag or in a motor vehicle.

[0009]Indeed, it is frequently necessary to have small rolls of tissue
paper available for journeys and it is common knowledge that the last
part of normal rolls of toilet paper or kitchen roll are often used for
this purpose, though they have the drawback of carrying a limited amount
of paper with respect to their overall dimensions (due mainly to the
unused volume of the tube or winding core in the middle). The nucleus of
the roll according to the invention, on the other hand, is a compact roll
of wound paper, with no waste of space.

[0010]The product obtained according to the invention consequently has the
characteristic of consisting substantially of a combination of two
independently usable products, generated by the same manufacturing
procedure and the same machine, but separable at the time of their use.

[0011]Instead of applying a separator product (be it in sheet or in the
form of loose material), provision can be made for an area of separation
to be created between the inner portion or nucleus of the roll and its
outer portion of the roll by means of a local variation in the density of
the winding. For instance, the winding density can be temporarily
reduced, even for just a very limited number of turns, thereby creating
an area of lower-density winding in the roll that separates the portion
of inner nucleus from the outer portion of the roll.

[0012]In another embodiment of the invention, between the inner portion or
nucleus and the outer portion, an adequate number of turns can be
inserted (or even only one turn, or a number of turns varying from 1 to
50, and preferably from 1 to 20, or from 1 to 10, or any adequate number
of turns) in which at least one surface characteristic of the web
material has been modified, e.g. the surface roughness has been reduced.
This can preferably be achieved by means of a calendering process on the
relevant stretch of web material.

[0013]Basically, and in general terms, therefore, the invention involves
the manufacture of rolls having a central nucleus or portion and an outer
portion, wherein an interface is created between the two portions, that
facilitates the mutual sliding between said inner and outer portions.

[0014]According to a further embodiment, the invention involves the
manufacture of rolls with a nucleus portion or central portion and an
outer portion, wherein there is a discontinuity between the two portions
that facilitates the mutual sliding between said inner and outer
portions. Thus, the invention also relates to a wound roll of web
material, preferably such as tissue paper, wherein two distinct portions
are obtained, an inner or central portion and an outer or peripheral
portion, capable of sliding mutually with respect to one another so as to
extract, or withdraw the first portion from the second. The roll is
preferably without a central hole or winding core and the central portion
of the roll consists of turns of web material wound one around the other.

[0015]In an advantageous embodiment, the web material has transversal
perforation lines, along which single sheets of web material e.g. tissue
paper, can be detached by the end user. In this case, it is advantageous
to provide for the separator material to be applied in line with one such
transversal perforation line on the web material. This facilitates the
tearing of the web material and consequently makes it easier to slidingly
extract the nucleus from the outer part of the roll, without disturbing
the turns of web material arranged in line with the interface between the
two portions of the roll.

[0016]The separator material can be applied to just one side of the web
material, or to both sides--in which case its application is preferably
staggered between the two sides, while a transversal perforation line is
preferably included in the area of overlap between the separator
materials applied on either sides of the web material. As explained in
the description provided with reference to several examples of embodiment
of the invention, this makes it easier to separate the two parts of the
roll.

[0017]The separator material may be a loose, liquid, semi-liquid or solid
material, applied to one or other, or both sides of the web material. For
instance, it may be a waxy material that makes the surface of the web
material suitably slippery, reducing its coefficient of friction in line
with the one or more turns that separate the central nucleus from the
outer portion of the roll, and thereby facilitating the mutual sliding of
the two parts in relation to one another.

[0018]The separator material will preferably be in the form of sheets,
however, made of a product with a relatively low friction coefficient,
e.g. compact paper, such as writing paper, photostat copier paper,
printer paper or the like, or a plastic with suitable features, a sheet
of waxed paper, or the like.

[0019]If the separator material is loose, it may be applied by spraying or
with a doctor blade or brushes, or other spreading means. When the
separator material is in the form of a sheet, on the other hand, it is
preferably anchored to the web material, e.g. with the aid of an
adhesive. Alternatively, it can be made to adhere to the web material by
mechanical crimping or ultrasound, embossing, electrostatic charging, or
any other suitable means.

[0020]The web material forming the roll is preferably paper, and
especially tissue paper, though this does not rule out the possibility of
applying the same inventive concept to the production of rolls of web
material of any other nature, such as plastic. Important is that, at the
point of separation between the nucleus and the remainder of the roll,
i.e. at the interface between the two portions required to slide with
respect to one another, the friction is lower than between the remainder
of the turns of wound web material. This enables the central nucleus to
slide out without producing any telescoping effect.

[0021]The diameter of the central nucleus of the roll can vary, depending
on the intended use of the roll. According to an advantageous embodiment,
it will be between 0.5 and 5 cm, and preferably between 1 and 3 cm. When
the web material to wind is tissue paper of the type generally used to
manufacture toilet paper or the like, a diameter of the inner nucleus of
approximately 20 mm equates to a length of approximately 1.5 m of wound
paper, a quantity sufficient for portable uses.

[0022]A perfume or lotion may be applied to the length of web material
forming the inner portion R1 of the roll, and/or to the separator
material.

[0023]According to another aspect, the present invention concerns a method
for manufacturing a roll of web material wound up without any central
winding core, comprising the following stages: [0024]curling the
leading end of said web material and winding it to form a first nucleus
of said roll with a first length of web material; [0025]generating an
interface, or discontinuity, e.g. by applying a separator material on at
least one side of said web material; [0026]continuing to wind on a second
length of web material to complete said roll.

[0027]According to yet another aspect, the invention concerns a rewinder
machine for the manufacture of a roll of web material wound up without a
central winding core, comprising a winding unit (preferably of peripheral
type), wherein the web material is wound up around its loose leading end
to form a roll with a central nucleus, and an outer portion is wound
around said central nucleus. Characteristically, the machine comprises a
device for generating an interface or discontinuity between an inner
portion and an outer portion of the wound material, said interface or
discontinuity facilitating the axial mutual sliding and consequent
separation of said two portions.

[0028]In a possible embodiment, this device comprises a device for
applying a separator material to the web material being wound onto the
roll, said applicator being operated so as to apply said separator
material after the formation of said central nucleus.

[0029]In a different embodiment of the invention, there may for instance
be a calendering device, which is temporarily enabled to generate a
length of Web material the surface of which is modified, i.e. preferably
made smoother, to form said interface. Generally speaking, along the path
along which the web material is fed to a winding cradle or a winding
unit, a device that changes at least one surface characteristic of the
web material in a pre-determinable portion of adequate length of said
material. According to a possible embodiment, this modified
characteristic consists in the roughness of the web material.

[0030]Further advantageous features. and embodiments of the roll, of the
method and of the rewinder machine according to the invention are stated
in the attached claims and are described in greater detail with reference
to several embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]The invention is better illustrated with the aid of the description
and the attached drawing, which shows examples of embodiments without
restricting the scope of the invention. To be more precise, in the
drawing:

[0032]FIG. 1 schematically shows a first embodiment of a rewinder
according to the invention;

[0033]FIG. 2 shows a modified embodiment of the rewinder according to the
invention;

[0034]FIG. 3 shows a further embodiment of the rewinder according to the
invention;

[0035]FIG. 4 shows a fourth embodiment of the rewinder according to the
invention;

[0036]FIGS. 5A to 5E show a working sequence of the rewinder in the
embodiment of FIG. 4;

[0037]FIGS. 6, 7, 8, 9, 10 and 11 schematically show a roll according to
the invention in various embodiments;

[0038]FIGS. 12 to 15 schematically show different methods for applying a
separator material in sheet form to the web material;

[0039]FIGS. 16 and 17 show a different embodiment of the machine according
to the invention; and

[0040]FIG. 18 schematically shows a side view of a machine in a further
embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0041]Referring initially to FIG. 1, in a first embodiment, the invention
involves the use of a rewinder configured (inasmuch as concerns the
winding elements) essentially as described in U.S. Pat. No. 5,639,046, to
which reference is made for a more detailed description of the structural
characteristics and operation of this type of rewinder.

[0042]FIG. 1 shows the essential parts of the winding head. The rewinder,
globally indicated by the numeral 1, comprises a first winder roller 3, a
second winder roller 5 and a third winder roller 7. The three winder
rollers form a winding cradle wherein a roll or log L is formed. The log
L formed by the rewinder is subsequently cut, crosswise to its own axis,
into single rolls of axial length corresponding to the length of the end
product.

[0043]The winder roller 7 is carried by oscillating arms 9 and is
gradually raised to enable and control the growth of the log L. The three
rollers 3, 5, 7 turn in the same direction (anticlockwise in the example)
at a substantially equal peripheral rate during the winding of the roll
or log L, while the speed of the lower winder roller 5, and possibly also
the roller 7 for controlling the diameter, varies (the former
decelerating, the latter accelerating) in the exchange phase, i.e. when
the completed roll or log L is unloaded and a new log L in the initial
winding stage is loaded according to methods that are known to those
skilled in the art.

[0044]A nip is created between the rollers 3 and 5, through which the web
material N to be wound up to form the roll or log L is passed (fed in the
direction of the arrow fN). Upstream from the nip between the rollers 3
and 5, there extends a concave surface 11 consisting of a curved sheet of
metal, carbon fiber reinforced resin or other suitable material. This
concave surface is provided with an oscillating movement in the direction
of the arrow f11 for pinching the web material N against the outer
surface of the winder roller 3, thereby inducing the tearing of the web
material and consequently prompting the central portion of a new log to
start being fashioned by means of the curling of the leading end of the
severed web material, as described in more detail in the
previously-mentioned U.S. Pat. No. 5,639,046.

[0045]The numeral 13 indicates a unit supporting the surface 11 and
capable of moving closer to, or further away from the roller 3 so as to
bring the surface 11 closer to, or further away from said roller. The
unit 13 also supports a control mechanism 15 driven by a motor 17 by
means of belts 19 and 21, for inducing a rapid pinching of the web
material N by the portion 11A of the curved surface 11 against the
cylindrical surface of the roller 3, as already described in the
previously-mentioned U.S. Pat. No. 5,639,046.

[0046]Along the path of the web material N being fed to the winding head,
there is a perforator, schematically indicated by the numeral 23, that
generates transversal perforation lines on the web material N to divide
the material into single portions detachable by tearing along the
perforation line when the finished roll is in use.

[0047]Characteristically, upstream from the inlet to the channel defined
between the outer surface of the winder roller 3 and the concave surface
11, there is a separator material applicator, consisting of a sheet
feeder indicated by the numeral 31 as a whole, the purpose of which is to
insert single sheets F of paper, plastic or other suitable material of a
given length at preset times along the feed path of the web material N.

[0048]The applicator 31 comprises a conveyor 33 with an associated suction
box 35 situated underneath the upper branch of the conveyor 33. One, or a
row of several nozzle(s), schematically indicated by the numeral 37, are
arranged along the conveyor 33 and, in a pre-established position on the
surface of the sheet F in transit on the conveyor 33, they apply an
adhesive in order to make said sheet adhere to the web material N in a
manner described later on.

[0049]Downstream from the conveyor 33, there is a roller 39 that is kept
constantly in rotation in a direction congruent with the direction in
which the web material N is fed forward, the path of which travels
between the roller 39 and the winder roller 3. The roller 39 is mounted
on oscillating arms 41 controlled by means of an actuator (not shown) so
as to push the roller 39 up against the roller 3 at a predetermined
moment to apply the sheet F to the web material N.

[0050]The sheet F is fed forward by the conveyor 33 until it occupies the
position schematically illustrated in FIG. 1, wherein the leading end of
the sheet F is withheld against the outer surface of the rotating roller
39, which can be perforated over its entire surface, for instance, and
maintained at a negative pressure on the inside by means of a fan. A
deflector 43 guides the sheet F so that it comes to rest correctly on,
and remain attached to the turning cylindrical surface of the roller 39.
The suction force exerted by the suction box 35 is stronger than the
suction exerted by the rotating roller 39, and consequently withholds the
sheet F up until it is inserted, in a manner described later on, in the
path of the web material N. As an alternative to the suction box 35,
there may be other types of retention means, e.g. mechanical devices.

[0051]With a configuration of this type, when the rewinder 1 has begun to
wind a new roll or log L and has formed the first central portion or
nucleus of said log, the roller 39 is pressed against the winder roller 3
and, since the two rollers turn at a peripheral speed corresponding to
the speed of the web material N, this makes the leading end of the sheet
F adhere to the web material N (due to the adhesive applied by the
nozzles 37) and induces the consequent forward feed of the said sheet F,
together with the web material N, towards the winding area where the log
L is formed. Thus, as will also become clear from a detailed description
of a sequence of operations, inside the log L being formed without a
central hole or winding core, there will be one or more turns formed by
the sheet F, consisting of a material with a low friction coefficient, or
in any case smoother than the web material N, which is typically tissue
paper for the preparation of rolls of toilet paper, kitchen paper or the
like.

[0052]For instance, the sheet F can be a sheet of plastic or even, more
simply, a sheet of printer paper, photocopier paper or the like,
typically. with a weight ranging between 25 and 100 g/m2. As will be
clarified in more detail later on, this paper--being smoother than the
tissue paper forming the web material N--enables the detachment and
extraction of the central nucleus from the outer portion of each roll
(obtained after cutting the log L created by the rewinder crosswise),
thereby creating a hole inside the finished roll.

[0053]FIG. 2 shows a rewinder 1 basically the same as the one described
with reference to FIG. 1, except for a different arrangement of the
feeder 31 of the sheets F. In this case, the feeder 31 is arranged on the
same side--vis-a-vis the path of the web material N--as the winder roller
3. The rotating roller 39 cooperates with a counter-roller 40, instead of
the winder roller 3, to perform the same procedure for applying the sheet
F on the web material N as it advances continuously and at a
substantially constant speed in the direction of the arrow fN. The letter
C indicates an adhesive applied by the nozzles 37 in the vicinity of the
leading end of the sheet F.

[0054]FIG. 3 shows a rewinder 1, much the same as the one shown in FIGS. 1
and 2, but provided in this case with two sheet feeders, indicated
respectively as 31A and 31B. The feeder 31A is made and arranged in the
same way as the feeder 31 of FIG. 1, while the feeder 31B is made and
arranged in the same way as the feeder 31 of FIG. 2. This configuration
enables the application of a sheet F on each of the opposite sides of the
web material N as it advances substantially continuously along its path
towards the winding cradle formed by the rollers 3, 5 and 7.

[0055]FIG. 4 shows an embodiment of a rewinder, again indicated by the
numeral 1, which has two feeders, indicated here as 51A and 51B, arranged
on either side of the path of the web material N, so as to attach two
sheets on said material N, as in the case of FIG. 3, one on each side.
The winding area of the rewinder 1 is substantially the same as the
winding area of the rewinder 1 shown in the previous embodiments.

[0056]Each of the two feeders 51A and 51B has a revolving suction roller
53, with holes 55 on its surface. The two rollers 53 of the two feeders
51A and 51B rotate in opposite directions, as described below with
reference to the sequence of FIGS. 5A-5E. Each roller 53 is associated
with a magazine 57 of sheets F and an adhesive distributor 59 consisting,
for instance, of a series of distributor nozzles. The rollers 53 can be
brought up against one another and, for this purpose, are supported by
oscillating arms (not shown) controlled by suitable actuators (not
shown).

[0057]The operation of the rewinder in the configuration of FIG. 4 is now
described in detail with reference to FIGS. 5A to 5E, the description of
which will also clarify how the rewinder functions in the embodiment of
FIGS. 1 to 3.

[0058]In FIG. 5A, a roll or log L is being formed between the winder
rollers 3, 5 and 7. The web material N advances in the direction of the
arrow fN at a substantially constant rate, while the rollers 53 of the
two feeders 61A and 53A wait and can each, in the meantime, collect a
sheet F from their respective magazines 57. The sheets F are held in
place on the outer surface of the two rollers 53 by suction. When the log
L has been completed with the winding of the pre-established quantity of
web material N, it is ejected, causing the tearing of the web material N
by means of the pinching of the surface 11 against the winder roller 3.
The contact between these two elements also makes the loose leading end
of the web material formed by said tearing action start to curl and
become wound around itself.

[0059]In FIG. 5B, the winding of a new log L begins, the previous roll or
log L having been completed and unloaded from the winding cradle 3, 5, 7.
The exchange stage and the start of the winding of a new roll are not
illustrated in detail because they are substantially equivalent to those
described in the earlier U.S. Pat. No. 5,639,046.

[0060]The rollers 53 are turned and their speed is accelerated up to a
peripheral speed substantially corresponding to the feed speed of the web
material N. A line of adhesive C has been applied in the vicinity of the
leading end of each of the two sheets F. The first sheet F, which is
attached to the side of the web material N facing towards the winder
roller 3, is applied by the feeder 51B, while the second sheet F is
applied by the feeder 51A to the opposite side of said web material N.
The two sheets adhere to the web material N due to the effect of the
adhesive C applied in the vicinity of the respective leading ends. The
attachment of the sheets is assured by the two rollers 53 pressing one
against the other, while they temporarily turn at a peripheral speed
corresponding to the forward feed speed of the web material N, thus
exerting a pressure on each of the sheets F and the web material N being
fed into the nip defined by the rollers 53.

[0061]In FIG. 5C the two sheets F have been applied to the web material N,
which continues to advance towards the winding cradle 3, 5, 7. As shown
in FIG. 5C, in this example the tail end of the sheet F applied by the
feeder 51B partially overlaps with the leading end of the sheet F applied
by the feeder 51A. This is not essential, however; in fact, it is
preferable for the two sheets to be a little distance away from one
another. In this latter case, the tail end of the first sheet and the
leading end of the second sheet, on opposite sides of the web material N,
leave a portion of the web material N uncovered that coincides with a
perforation line P created by the perforator 23 on the web material N
(see FIG. 1, and the embodiment of FIG. 4). There may also be a partial
overlap between the first and second sheets, as shown in the drawing. The
important thing is for a perforation line P in the web material N to come
between the two lines of glue applied to the two sheets.

[0062]In FIG. 5D the two sheets F come to be in the area of the web
material wound around the winder roller 3 and are about to be wound
around the initial nucleus of the new roll or log L being formed in the
winding cradle 3, 5, 7.

[0063]FIG. 5E shows how the log L further increases in diameter and the
sheets F come to be inserted between the initial turns of the roll or log
L, separating the central nucleus portion of the log indicated as L1,
from the outer portion of the log L, indicated as L2. As we be explained
later on, the finished rolls obtained after cutting the log L crosswise
are compact and have no winding hole, but the inner portion of each roll,
corresponding to the nucleus L1 portion of the log from which they were
cut, can be extracted from the outer portion of said roll to generate a
roll with a central hole and consequently similar to a roll obtained
using conventional winding systems using tubular cores.

[0064]In fact, the sheets F applied to the web material N define surfaces
of separation, or interfaces between overlapping turns of the web
material N forming the log L, and consequently also the rolls obtained by
cutting said log, and the layers can mutually slide along said separation
surfaces, tearing the web material N along the perforation line P in the
area between the tail end of one sheet F and the leading end of the
opposite sheet F, i.e. between the two points where the sheets F are
joined to the web material N.

[0065]This concept is illustrated schematically in FIGS. 6 and 7. To be
more precise, FIG. 6 shows a considerable enlargement of the internal
area of a roll R obtained after cutting the log L crosswise, wherein R1
indicates the inner portion or nucleus and R2 indicates the outer portion
surrounding the nucleus, said portions corresponding to portions L1 and
L2 of the log L from which the roll R was obtained.

[0066]LI indicates the leading end of the web material N. F1 indicates the
sheet applied by the feeder 51B or, to be more precise, the strip of said
sheet remaining inside each roll R, after it has been cut from the log L.
This sheet forms at least one turn (in the example illustrated, but it
could form several turns), which completely surrounds the nucleus or
initial portion R1 of the roll R. The sheet F2, corresponding to the
sheet F applied by the feeder 51A, is arranged with its leading end (i.e.
the innermost end) in the vicinity of the perforation line P and also
forms one or more turns inside the roll.

[0067]By exerting a pressure on the flat outer surface of the nucleus R1
of the roll R, thus overcoming the mutual friction between the two sheets
F1 and F2, the inner portion R1 slides out of the outer portion R2,
tearing the web material N along the perforation line P created between
the two overlapping ends of the sheets F1 and F2. This makes the inner
nucleus R1 of the roll slide out of the outer portion R2 in such a manner
that the latter has the appearance of a normal roll of paper wound around
a tubular core. The portion of nucleus R1 remains wrapped in one or more
turns formed by the sheet F1, while the wall of the hole created in the
portion R2 of the roll is lined with the sheet F2.

[0068]When the log L is formed with a rewinder of the type illustrated in
FIG. 1, wherein only one sheet F is applied to the surface of the web
material N that faces inwards, i.e. towards the axis of the log, the
products obtained will be as illustrated in FIGS. 8 and 9. The central
portion or nucleus R1 of the roll R is wound, in the example illustrated,
in approximately one turn of the material forming the sheet F, the
innermost end of which approximately coincides with a perforation line P.
Pushing axially on the inner portion R1 of the roll R again enables the
inner portion to be extracted due to sliding between the first turn of
the outer portion R2 of the roll and the sheet F, which remains attached
to the inner portion R1 of the roll R. FIG. 9 shows how, once the inner
portion R1 has been extracted from the outer portion R2 of the roll, the
hole in the outer portion R2 remains lined with the sheet F.

[0069]Vice versa, FIGS. 10 and 11 illustrate the situation in which the
sheet F is attached to the other side, i.e. to the side of the web
material N facing outwards, with a rewinder configuration of the type
shown in FIG. 2. The perforation line P comes to be in the vicinity of
the tail end of the sheet F. Pushing axially on the nucleus R1 makes it
slide out of the outer portion R2, leaving the latter with an unlined
hole in the middle, while the extracted inner portion R1 is lined with
the sheet F adhering to said nucleus.

[0070]In the above-described examples, the assumption is that an adhesive
is applied in the vicinity of the leading end of the sheet of separator
material, i.e. to the end further forward with respect to the direction
in which the web material is being fed forward. As mentioned previously,
however, this is not the only way to anchor a sheet of separator material
to the web material. For instance, said anchorage may be obtained by
means of a mechanical crimping or ultrasound, electrostatic charging,
embossing, or by any other means. When such alternative options are used,
it is advantageous to provide for the mutual adhesion between the sheet
material and the web material to extend approximately over the full
length of the sheet material.

[0071]When an adhesive is used, on the other hand, said adhesive may also
be applied in several spots and not only in the vicinity of the leading
end of the sheet material.

[0072]Figures from 12 onwards schematically show methods for applying the
adhesive in several spots. In each figure, N indicates a portion of the
web material advancing in the direction of the arrow fN; the letter P
indicates a perforation line along which the web material N wound on the
roll is torn when the two portions R1 and R2 are subjected to a force to
extract the former from the latter. The letter F indicates the sheet of
separator material when only a single sheet is used, while F1 and F2 are
used to indicate the two sheets of separator material when two sheets of
said material are used in the same roll R.

[0073]FIG. 12 shows the position for applying a sheet F on the web
material N so that it remains wrapped around the nucleus R1 of the roll
R. In this case, the sheet is attached with two areas of adhesive C1 and
C2, applied in the vicinity of the leading end Lt and tail end Lc of the
sheet F. With a double crosswise line of adhesive C1, C2, the sheet F
remains attached to the inner nucleus R1, thus keeping it wound even when
it has been completely removed from the outer portion R2. The perforation
line is in the vicinity of the tail end Lc, downstream from the line of
adhesive C2. Said adhesive may seep through to anchor the last turn of
the portion R1 to the inner turn. It can also be applied to the side of
the web material N opposite the side to which the sheet F is attached and
spread so as to make the latter adhere to the web material N.

[0074]In FIG. 13 the sheet F is applied to the opposite side of the web
material N, downstream from the perforation line P, here again with two
areas of adhesive C1 and C2, in the vicinity of the leading end Lt and
tail end Lc, respectively. The adhesive C2 can serve to avoid any loss of
control over the tail end Lc.

[0075]FIGS. 14 and 15 show two methods for applying two sheets of
separator material F1, F2 to the web material N. In the first case, the
perforation line P comes to be between the tail end Lc of the first sheet
F1 and the leading end Lt of the second sheet; the two sheets F1, F2 do
not overlap. The sheet F1 is anchored by means of two spots of adhesive
C1 and C2. A second spot or line of adhesive C2' can be applied on the
side opposite the side on which the sheet F1 is applied. A similar
solution can also be adopted in the case of FIG. 12, here again so as to
attach the loose end of the portion R1 of the roll.

[0076]In FIG. 15 the tail end Lc of the sheet F1 overlaps the leading end
Lt of the sheet F2, with the perforation line P coming between the two.

[0077]Generally speaking, when a single sheet of separator material F is
used, it can be attached either to the portion R1 or to the portion R2 of
the roll R, depending on its position with respect to the perforation
line P and the position of the adhesive C1.

[0078]In the various examples illustrated above, it is assumed that a
single sheet of separator material is applied to one side of the web
material N, or two sheets are applied, one on each side. Alternatively,
in addition to using a separator material other than in the form of
sheets, e.g. a waxy material applied in the form of a spray, one or more
sheets of separator material can also be applied at intervals, the global
coverage of which might equate to one turn of web material, or less. In
fact, covering an area corresponding to half or two thirds of the length
of one turn, for instance, with separate material is sufficient to obtain
a mutual sliding between the portions R1 and R2 of the web material.

[0079]According to a preferred embodiment of the invention, the separator
material--be it in the form of a sheet material or of a loose material
distributed over the surface of the web material--is suitable for
dissolving or dispersing in water so that it can be disposed of directly
in the WC.

[0080]Instead of using additional distributors or applicators of the
separator material, in a possible alternative embodiment, the separator
material for wrapping around the central nucleus R1 could be applied
using the mobile-axis winder roller 7. A solution of this type is
illustrated in FIGS. 16 and 17. The same numbers indicate parts
corresponding or equivalent to those of the embodiment in FIG. 3. The
upper winder roller 7 is associated with a sheet feeder 31B that, in the
schematic illustration in the drawing, comprises a surface 34 for
delivering the sheets F, which can be fed forward by means of feed
rollers (not shown), or belts, or by any other means, and can consist of
pre-cut sheets or lengths of a material in sheet form delivered from a
reel. Two lines of adhesive C1 and C2, which may or may not be
discontinuous, are applied to the sheet F, one in the vicinity of the
leading end Lt and one in the vicinity of the tail end Lc. The feed plane
is set at a level (which may be adjustable) so that the mobile roller 7
comes to be into the vicinity of said plane when the completed log L is
unloaded from the winding cradle (FIG. 16). In this position, possibly
after an upward overtravel of the oscillating arms 9 supporting the
roller 7, the leading end Lt of the sheet F is engaged by suction on the
roller 7, which has a suction segment 7A. At this point, the central
nucleus L1 of the next log L begins to form and reaches or has passed
through the nip between the winder rollers 3 and 5, but it has not yet
reached the diameter required for the portion L1.

[0081]FIG. 17 shows the next stage, wherein the log L has been unloaded
and the roller 7 has been lowered, bringing the sheet F with its leading
end Lt into contact with the initial portion of the currently forming
roll. The peripheral speed, angular position and lowering movement of the
roller 7 are phased so as to induce the anchorage of the leading end Lc
by means of the adhesive C1 on the outermost turn of the portion L1 of
the nucleus that has been formed. The tail end Lc can be glued by means
of the adhesive C2 (if any), or remain loose, since it is engaged and
held in place in any case by the next turn of the web material N.

[0082]There may be a feeder 31A, in which case it works as explained with
reference to FIG. 3 and serves the same purpose. Said feeder may also be
omitted, however.

[0083]In the previously-described embodiments, an interface is created
between the nucleus or inner portion R1 of the roll and the outer portion
R2 of the roll by applying a separator material, typically in the form of
a sheet adhering to the web material. The separator interface between the
two concentric portions of each roll can also be generated by other
means, however. For instance, a localized change can be made to the
roughness or any other characteristic of the surface of the web material
(preferably affecting the friction coefficient) over a stretch of
material corresponding to approximately half a turn, or a full turn, or
even a number of turns, e.g. 2 or 3 turns, or an even larger number of
turns, for instance coming between 1 and 50, and preferably between 1 and
20, between the inner portion and the outer portion of the roll.

[0084]The web material (typically tissue paper) can, for instance, be
calendered to make it smoother. FIG. 18 schematically illustrates a
rewinder machine substantially similar to the one in FIG. 4, wherein the
system for feeding the sheets F is omitted and replaced by a calendar 200
comprising two rollers 201 and 203. In the example illustrated, the
roller 201 has a cylindrical lateral surface of constant radius, while
the roller 203 has a portion 203A that is larger in diameter. Thus, the
roller 201 can be kept turning constantly, while the roller 203 only
turns when the interface needs to be generated between the two (inner and
outer) portions of the roll or log. By rotating the roller 203, even
through just one turn, the portion 203A is pressed against the roller
201. The radius of said portion 203A is such that said portion squeezes
and thereby calenders the web material N. This calendering action is
performed over a portion of material, the length of which equates to the
length of the portion 203A.

[0085]Alternatively, the two rollers 201, 203 can have constant diameters
and be pressed one against the other at a suitable time. The roller 201
can be kept turning continuously or, like the roller 203, it can be
turned only when the calendering of the web material is required.

[0086]The interface between the inner and outer portions of the roll or
log can also be generated by means of a localized variation in the
density of the winding. This can be achieved by modifying the pressure
exerted by the roller 7 on the roll or log L, or by adjusting the turning
rate of the rollers, or by combining these effects.

[0087]FIG. 18 shows a further possible characteristic of the machine
according to the invention. This consists in the presence of a cutting
roller 301 complete with a cutter blade 301A or other cutting means,
cooperating with a counter-blade or groove 303 in the surface of the
winder roller 1. The cutting roller 301 can be brought up to and drawn
away from the roller 1 so that the blade 301A only cooperates with the
counter-blade 303 when a crosswise cut is required. Alternatively, the
cutting roller can be made to complete only one turn when a cut is
required. In this way, a crosswise cut can be made in the web material in
line with the area of said material coinciding with the interface or
discontinuity between the inner and outer portions of the roll. This will
facilitate the mutual sliding between the two said portions. A portion of
cylindrical surface of the winder roller 1 on the two sides of the
counter-blade 303 is perforated and in communication with a suction box,
enabling the resulting suction effect to retain the ends of web material
generated by the cutting action so that they can be transferred to the
area where the roll or log is being formed.

[0088]Alternatively, especially if no perforation of the web material is
required, the blade 301A can be serrated to generate a single perforation
line in each roll, coinciding with the area of the interface or
discontinuity that separates the two, inner and outer portions of the
roll. Both a single transversal perforation in the area of the interface
between the inner and outer portions, and perforation lines dividing the
web material into single detachable sheets can be made in this way. This
method can be used to create a more marked perforation line in the area
of the interface or discontinuity, thereby facilitating the extraction of
the inner from the outer portion of the roll.

[0089]It should be understood that the drawing only illustrates one
example, given simply as a practical demonstration of the invention,
which may vary in the forms and arrangements, without departing from the
concept of the invention. Any reference numbers in the attached claims
are merely for the purpose of facilitating the reading of the claims with
reference to the description and the drawing, and shall not restrict the
coverage of the patent as represented in the claims.